1. Field of the Invention
The present invention relates to a frameless torque motor with a transport securing device, wherein the torque motor has a ferromagnetic primary element and a secondary element with magnets oriented in the direction toward the primary element, which are maintained spaced apart by a transport securing device.
2. Discussion of Related Art
Such torque motors are employed to solve problems in many modern drive mechanisms.
Torque motors are described in EP 793 870 B2, which have a number of magnets on a rotor and a number of coils on a stator on teeth of a core. Such torque motors can create a high torque even with a low number of revolutions. This allows extremely even movements and an excellent capability of regulating the speed. Since the load is coupled directly to the motor while force transmission elements are omitted, these systems offer great dynamics, rigidity and accuracy of regulation superior to all conventional drive mechanisms. Torque motors lower the operating costs, simplify the construction of the machine, show no wear and do not require any maintenance.
Frameless torque motors are directly integrated into the respective application. The position of the rotor and the stator in relation to each other is not defined by a bed of the torque motor of its own, but directly by the structural design of the application. For example, typical applications are turntables or pivot shafts of machine tools, telescopic drive mechanisms or automatic assembly machinery.
Occasionally the rotor and stator of a torque motor are delivered separate from each other. However, for the user this means that he himself has to adjust the parts with respect to each other. This is not an easy job because of the high degree of attraction between the rotor and stator. Customarily such a motor is delivered by the manufacturer already pre-adjusted.
Since torque motors do not have their own bed or do not have their own frame, it is necessary that the rotor and stator are maintained with respect to each other by different devices. Customarily a so-called motor bridge is used as a transport securing device. This includes one or several elements, which are screwed together with the rotor and stator along their circumferences after these had previously been aligned with each other by a centering device.
Since the magnets customarily used in torque motors are very strong, the motor bridges are mostly made of a non-magnetic material, such as aluminum, for example. In this way the motor bridges can be aligned with respect to the motor and fastened without problems. Since the magnetic force between the magnets of the rotor and the core of the stator is very strong, the motor bridges must be made very sturdy. It is absolutely necessary to prevent the magnets of the rotor from touching the core of the stator. The separation of the parts would be very difficult to do. Thus, such motor bridges are relatively elaborate and expensive. It is therefore necessary to return them to the manufacturer of the torque motor after the latter has been installed, which results in a not inconsiderable logistic outlay.
Moreover, such motor bridges hamper the installation of the torque motor in the respective application. It is necessary for the screws for releasing the motor bridge to be still accessible after the motor has been placed in the respective application. There must also be a way to remove the motor bridge. This makes considerable demands on the entire construction. Often the rigid connection between the rotor and the stator makes the installation more difficult, so that the motor bridge must first be loosened for definitely adjusting the installation position and for fixing it in place. Only then can the motor bridge be definitely removed.